A power module is a device in which a pair of switching elements are connected in series to a power supply to obtain an output from between the pair of switching elements. Such a power module is, for example, used for an inverter circuit which forms a driving circuit to drive an electric motor. The electric motor is used as, for example, a power source of an electric vehicle (including a hybrid car), a train, an industrial robot and the like. The power module is also applied to an inverter circuit that converts electric power generated by a solar battery, a wind power generator and other power generators (particularly, a private electric generator) so as to match the electric power of a commercial power supply.
For the switching elements of power modules, devices using Si (silicon) semiconductors have been conventionally used. However, there has been a problem of losses in the devices at the time of power conversion, and the situation is that a further improvement in efficiency of the devices using Si materials is no longer feasible.
Therefore, a power module using, as its switching elements, power devices using SiC (silicon carbide) semiconductors has been proposed. The SiC power devices are capable of conducting a high-speed ON/OFF operation because switching speed is high. Consequently, a current quickly decreases at the time of switch-off so that switching loss can be reduced.